1. Field of Invention
A primary field of the invention is industrial spraying equipment to clean, rinse, and/or chemical-treat articles of manufacture. The spraying takes place in a confined area, such as a spray or washer booth, in which various liquids are piped under pressure through horizontal overhead or bottom feed pipes, called headers, into a plurality of vertical pipes, called risers, connected to the headers, and then out through nozzles which are attached to the risers and which are adapted to spray workpieces in the washer booth.
Another field of the invention is fire protection water sprinkler systems.
Yet another field of the invention is agricultural irrigation and sprinkler systems.
2. Description of Related Art
Prior art washer booths are customarily made of steel, and are basically rectangular, with means for a parts conveyor to pass through. They are usually equipped with a pair of header pipes spaced apart and running parallel and longitudinal to the washer booth floor or ceiling. Industrial liquids are stored in a tank underneath the washer booth floor and pumped through suitable plumbing to the headers. A bank of risers is connected to each header, extending vertically upward or downward along an adjacent washer booth wall. Several nozzles are secured to each riser of each bank of risers and are aimed inwardly to spray workpieces being conveyed between opposed banks of risers.
Prior art headers have universally been cut to length from a single piece of steel or extruded chlorinated polyvinylchloride (CPVC) pipe, customarily supported against bending every five feet of horizontal length. CPVC, for about half the material and labor costs of steel, has to a large extent replaced steel for low temperature washing up to 180.degree. F., but CPVC cannot be used for bath temperatures in excess of that temperature. Because of the corrosiveness of the phosphates, stainless steel headers have been used for second stage pretreatment, which consists of spraying the metal work products with a metallic coating from the phosphate family, such as zinc or iron. Applicant's U.S. Pat. No. 5,257,739 teaches the use of glass-filled polyolefin, which is resistant to corrosives and withstands high bath temperatures up to 220.degree. F., for molded segmented risers, but polyolefin has not been used heretofore for headers, which are much larger and heavier than risers. Risers have approximately one-fifth the diameter of headers, and their vertical positioning incurs substantially no bending stress. Polyolefins must be glass-filled for strength, and glass-filled polyolefins are not extrudable. The technique of connecting vertically positioned polyolefin riser segments is not transferable to the connecting of header segments because header joints are subject to bending stresses which segmented riser pipe joint cannot withstand.
Because CPVC headers and polyolefin risers are incompatible, they cannot be glued, welded, molded, or otherwise bonded together. Accordingly, they must be secured together with special clamp connectors or by threading. Molding CPVC headers for attachment to polyolefin risers with special connector fittings is not economically feasible because of the high cost of tooling. Furthermore, securing polyolefin risers to steel headers requires two separate skills, plastic pipe fitting and steel pipe fitting, and is therefore labor intensive.
Recently it has been discovered that CPVC develops so-called "chemical stress cracks" due to an increasingly higher percentage of surfactants in use in some cleaning stages of washers. These cracks may begin to occur after six to twelve months of operation. As a consequence, some industrial users of chemicals for cleaning and treating metal parts have discontinued the use of CPVC in their washer piping systems and have returned to the use of black iron or stainless steel pipes.
There are several other disadvantages to the use of one-piece headers, whether steel or CPVC. They must be custom cut to length from standard longer pieces, which leaves considerable unusable scrap. Also, if the header becomes obstructed, the entire assembly of header, feeder pipes, and risers must be disassembled in order to remove the obstruction. If any portion of the header should be defective, the entire header must be scrapped. Since the locations of riser connectors must be predetermined and custom pre-drilled, replacement of a header requires that all connecting risers be custom fitted to the replacement header. These are all expensive, labor-intensive procedures.
Furthermore, interstate transportation is difficult due to the length of prior art one-piece headers twenty feet or longer, and overseas shipment is particularly difficult.
Applicant's invention of glass-filled polyolefin header pipe segments with novel molded connectors permits the use of all-polyolefin pipe installations, at less cost and less installation time than prior art steel or CPVC installations.